Use of transition metal carbonyls as catalysts in preparing cyclopentadienyl manganese tricarbonyl



Um'ted States Patent USE OF TRANSITION METAL CARBONYLS AS CATALYSTS IN PREPARING CYCLOPENTA- DIENYL MANGANESE TRICARBONYL Tillmon H. Pearson and John K. Presswood, Baton Rouge, La., assignors to Ethyl Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed Apr. 25, 1958, Ser. No. 730,787

3 Claims. (Cl. 260-429) This invention relates to the manufacture of cyclopentadienyl manganese compounds and more particularly to the manufacture of cylopentadienyl manganese tricarbonyl compounds.

Cyclopentadienyl manganese tricarbonyl compounds have been found to be exceptionally effective antiknocks for use in fuel for spark plug ignition internal combustion engines. These compounds not only have exceptional effectiveness as antiknocks but also many of these compounds have auxiliary properties which make them practical and desirable for commercial use. These auxiliary properties include high solubility in fuels, such as gasoline, and thermo-stability either alone or in gasolines which makes these compounds entirely satisfactory for use under the widely varying conditions to which gasoline and other fuels are normally subjected. Possibly of even greater importance these compounds do not tend to form any appreciable deposits on the engine pistons, valves and spark plug surfaces and likewise are not abrasive to the engine parts as are characteristic of iron compounds.

It is accordingly an object of this invention to provide an improved process for the manufacture of cyclopentadienyl manganese tricarbonyl compounds. Another object is to provide a process of the above type using inexpensive raw materials and utilizing a minimum of process steps. Still another object is to provide a process which gives improved yields of the desired product. Another object of this invention is to provide a process which has exceedingly fast reaction rates. Other objects and advantages of the invention will be more apparent from the following description and appended claims.

It has now been found that cyclopentadienyl manganese tricarbonyl compounds can be produced in excellent yields by reacting a manganese compound simultaneously with a cyclopentadiene hydrocarbon and gaseous carbon monoxide at a pressure of from about 25 to 8000 p.s.i.g. if the reaction is conducted in the presence of a transition metal carbonyl, i.e. metals of groups V-B, VI-B, VII-B, and VIII of the periodic table, and also in the presence of an elemental metal of groups H and III-A of the periodic table (see the Periodic Table in Handbook of Chemistry and Physics, 36th Edi, pages 392 and 393).

More specifically, the process of this invention comprises reacting the cyclopentadiene hydrocarbon and manganese compound with carbon monoxide, preferably in a liquid media which is a solvent for the manganese compound, in the presence of from about .01 to 50 moles percent of the transition metal carbonyl. Somewhat lower concentrations can be employed but the benefits of the metal carbonyl are also diminished. Likewise, higher concentrations of the metal carbonyl can be employed but the resulting improvement in the process is not greatly increased and is accordingly uneconomical. The process is preferably conducted at a temperatume of from about 75 to 250 Q, although the process can be conducted over a temperature range of about to 300 or such temperatures wherein the reactants and products are stable. The manganese compound and cyclopentadiene hydrocarbon are preferably employed in about stoichiometric quantities, it being frequently preferred to employ the cyclopentadiene in excess, e.g. from 50 to 30 percent. The carbon Patented June 6, 1961 monoxide can be used at from subatmospheric to superatmospheric pressures although it is preferred to use pressures ranging from about 25 p.s.i.g. to about 8000 p.s.i.g. Higher pressures can be employed to increase the reaction rate, although, very surprisingly, the very high pressures, i.e. above about 10,000 p.s.i.g., appear to lower the product yield.

The cyclopentadiene hydrocarbon can be used in monomer form or can also be used as a dimer. When using the dimeric cyclopentadiene hydrocarbon it is frequently desirable to conduct the reaction at the more elevated temperatures, i.e. at temperatures above about 150 C.

The eflectiveness of the transition metal carbonyl compounds in the process of this invention is very surprising and in fact the reaction mechanism is not understood. In the absence of the transition metal carbonyl, the yield of the cyclopentadienyl manganese tricarbonyl compounds is very low, usually below about 5 percent based upon the manganese compound. In contrast, in the presence of even small quantities of the transition metal carbonyl, the yields of the desired cyclopentadienyl manganese tricarmonyl increase many fold. This unexpected phenomena is apparently not due to the mere donation of carbonyl groups to the manganese metal by the transition metal carbonyl employed in the process since the reaction does not proceed readily in the absence of gaseous carbon monoxide. The presence of very high pressures of carbon monoxide results in an apparent depressing effect on the reaction would indicate that the reaction mechanism has something to do with the metal carbonyl decomposition and therefore it is possible that some decomposition is necessary to the actual effectiveness of the metal carbonyl in this reaction.

The compounds which can be made by the process of this invention are any cyclopentadienyl manganese tricarbonyl compounds, including substituted cyclopentadienyl compounds, such as the indenyl and fluorenyl derivatives. Typical examples of such compounds are cyclopentadienyl managanese tricarbonyl, methylcyclopentadienyl manganese tricarbonyl, n-butylcyclopentadienyl manganese tricarbonyl, isobutylcyclopentadienyl manganese tricarbonyl, n-decylcyclopentadienyl manganese tricarbonyl, phenylcyclopentadienyl manganese tricarbonyl, methylphenylcyclopentadienyl manganese tricarbonyl, indenyl manganese tricarbonyl and fluorenyl manganese tricarbonyl. For fuel use, the preferred compounds are those containing up to about 12 carbon atoms in the cyclopentadienyl group.

The elemental metal of groups H or III-A is employed in a concentration of from about molar equivalence to about percent excess, based upon the manganese compound. Even greater excesses can be employed without effecting the reaction but, in general, this is uneconomical and creates problems in recovery of the product. Lesser quantities, i.e. 0.5 mole per mole of manganese compound, can be used but poorer results are obtained.

The liquid media suitable for the process of this invention can be any solvent or complexing agent for the manganese compound. In general, suitable solvents are ethers, amines, amides, nitriles, and the like. The ethers can be either aliphatic or aromatic, such as dimethyl ether, diethyl ether, methylethyl ether, anisole, diphenyl ether and, in general, any ether which is liquid at the reaction temperature and pressure employed. Preferred ethers are diisopro'pyhand the like. In general the preferred ethyl-f 3 one glycol dialkyl ethers have alkyl groups containing from 1 to 6 carbon atoms.

Suitable amine solvents for use in this invention are propyl amine, diethyl amine, di-n-p'r'op'yl amine, dib'ut'yl amine, triethyl amine, triisopropyl amine; and other amines having from 2 to 10 carbon atoms'per alkyl group. Aromatic amines are also suitable, such as aniline methyl aniline, dimethyl aniline, trimethyl' aniline, and similar compounds. A particularly suitable amine solvent is dicyclohexylamine.

Typical examples of suitable amides are formamide, and the monoand dialkyl formamides, such as' N,N- dimethyl formamide, containing alkyl' groups having from 1 to 6 carbon atoms. Other suitable" amides are cyclic amides, such as' N-methyl pyrrolidone and other alk'yl pyr-rolidones, and amides of inorganic acids; such as hexamethyl phosphoramide. I 7

suitable'nitriles which canbe'ernployed'as sol vents'in this invention are acetonitrile, prop'ionit'rile; butyr'onitrile and'the like.

The liquid media can be employed in a widerang'e of concentration from about 0.5 mole, based upon the man'- ganesc compound, to about 30 moles. Higher dilution of the reaction mixture can be employed except that no appreciable improvement in the reaction is obtained and considerably greater difficulty is encountered in the recovery of the desired product.

Any of the manganous compounds can be employed in this invention, such as the oxide, sulfide, halide, including the chloride, bromide, iodide, and fluoride, sulfate, carbonate, nitrate. Of these, the halides are preferred andespecially the chloride. The organic compounds of manganese are also useful in this invention including manganous formate, acetate, propionate, butyrate, oxalate, tartrate, and other salts of organic acids having up to about 10 carbon atoms;

The metals of groups H and III-A are preferably employed inthe process in an active form. Best resultsare obtained when the metal is finely divided, that is having a particle size ranging from about microns up to par ticles having 2 to 4 millimeters in thickness. The metal preferably should have a clean surface, essentially uncontaminated with an oxide coating. It is found that powdered metals available commercially are very suitable.

The following examples illustrate the process of this invention. All parts are given as parts by weight.

Example I" To a reaction vessel equipped with meansfor agitating the reaction mixture was added 4 parts of manganese chloride, 2 parts of magnesium metal powder, '4 parts of methylcyclopentadiene dimer, l part of'iron pentacarbonyl, and 50 parts of N,N-'dimethyliformamide. The reactor wasthe nsealed and pressurized to 3500 p.s.i.g. with gaseous carbon monoxide and the reactionv mass heated with agitation to a temperature of 195 C. for one hour. The reactor was then cooled and" the reaction product steam distilled to recover the desired methylcyclopentadienyl manganese tricarbonyl. The product was obtained in about 28 percent yield, based upon the manganous chloride charged to the reactor. This compares with only about 2 percent yield when the reaction is conducted in the absence of iron pentacarbonyl. The purified methylcyclopentadienyl manganese tricarbonyl has exceptional antiknock effect when used'in fuels, employed, for example, in accordance with the procedures given in US. Patent 2,818,417.

Exam le 11- Twas repeated except" thatfthe' reaction tank perature was maintained at 225 C; 3 'hours'iof reaetiontimewas' employed." Similarresultswere obtained:

4 Example III Example I was repeated except that 2 parts of iron pentacarbonyl were employed and essentially the same yield of the desired product was obtained.

Example IV Example V Example I was repeated except that a lower pressure of carbon monoxide was employed, i.e. 1000 p.s.i.g. Similar results were obtained except that the yield of methylcyclopentadienyl manganese tricarbonyl was somewhat lower than in Example I.

I Example VI High, pressures of carbon monoxide were employed to illustrate its effect on the formation of the desired product. When employing a pressure of 8200 p.s.i.g. of carbon monoxide, the yield dropped drastically, giving only 0.5 percent yield based upon the manganese compound chargedl With pressures of 12,900 p.s.i.g. of car bon monoxide the yield was only 0.2 percent.

Example VII Example I is repeated except that cyclopentadiene monomer is reacted with manganous acetate and carbon monoxide (1500 p.s.i.g.) in the presence of metallic beryllium (2 moles) and vanadium carbonyl (1 mole percent). Thereaction is conducted in N-methyl pyrrolidone at Example VIII N-butyl cyclopentadiene is reacted with manganous oxide and carbon monoxide (2000 p.s.i.g.) in the presence of calcium metal andchromium hexacarbonyl according to the procedure of Example I. Diethylene glycol dimethyl ether (5 moles per mole of the manganese compound) is employed as the solvent and the reaction is conducted at 250 C. The n-butylcyclopentadienyl manganese tricarbonyl is recovered in good yield.

Example IX Exa'mpleX Methylphenylcyclopentadiene is reacted with manganous iodide and carbon monoxide (5000 p.s.i.g.) in the presence of 2 mole equivalents of cadmium metal and 10 mole percent of Fe (CO) This reaction is conducted in dicyclohexylamine solvent at a temperature of C. The methylphenylcyclopentadienyl manganese tricarbonyl is distilled from the reaction product, after removal of the solvent. The final distillation of product is conducted in the presence of an equal volume of a high-boiling hydrocarbon (a petroleum fraction) to suspend the inorganic impurities.

Example XI Indene is reacted with manganous oxalate in hexamethyl phosphoramide in the presence of 5 mole equivalents of boron metal and 1- mole percent of cobalt carbonyl. The reaction is conducted at 300 C. The indenyl manganese tricarbonyl product is recovered in excellent yield.

Example XII Pluorene is reacted with manganous sulfide and carbon monoxide (1800 p.s.i.g.) in the presence of 1.5 mole equivalent of aluminum metal (powdered) and 20 mole percent of nickel carbonyl. The reaction is conducted in tetrahydrofuran solvent moles per mole of manganous sulfide) at a temperature of 90 C. The fluorenyl manganese tricarbonyl is recovered by distillation.

In the above examples the cyclopentadiene hydrocarbon and metal carbonyl have been reacted directly with the manganese compound. With certain of the metal carbonyls which form complexes with cyclopentadiene, such as the complex dicyclopentadienyl diiron tetracarbonyl, the complex can be used directly in the reaction.

We claim:

1. The process for the manufacture of a cyclopentadienyl hydrocarbon manganese tricarbonyl comprising simultaneously reacting a manganese salt with a cyclopentadiene hydrocarbon, carbon monoxide and a metal selected from the group consisting of groups 11 and III-A of the periodic table while in contact with from about 0.01 to about 50 mole percent of an inoganic transition References Cited in the file of this patent UNITED STATES PATENTS 2,557,744 Hurd June 19, 1951 2,748,167 Hagemeyer et al May 29, 1956 2,810,736 Catlin et al Oct. 22, 1957 2,818,417 Brown et al. Dec. 31, 1957 2,870,180 Kozikowski et al Ian. 20, 1959 2,898,354 Shapiro et al Aug. 4', 1959 2,916,504 Shapiro Dec. 8, 1959 OTHER REFERENCES Deming: General Chemistry, 5th edition, New York, John Wiley and Sons, Inc., copyright 1944, last page relied on. 

1. THE PROCESS FOR THE MANUFACTURE OF A CYCLOPENTADIENYL HYDROCARBON MANGANESE TRICARBONYL COMPRISING SIMULTANEOUSLY REACTING A MANGANESE SALT WITH A CYCLOPENTADIENE HYDROCARBON, CARBON MONOXIDE AND A METAL SELECTED FROM THE GROUP CONSISTING OF GROUPS II AND III-A OF THE PERIODIC TABLE WHILE IN CONTACT WITH FROM ABOUT 0.01 TO ABOUT 50 MOLE PERCENT OF AN INOGANIC TRANSITION METAL CARBONYL, SAID TRANSITION METAL BEING SELECTED FROM THE GROUP CONSISTING OF GROUPS V-B, VI-B, VII-B AND VIII OF THE PERIODIC TABLE, SAID CARBON MONOXIDE BEING EMPLOYED AT A PRESSURE OF FROM ABOUT 25 P.S.I.G. TO ABOUT 8,000 P.S.I.G. 